OpenCV Android解决相机旋转90度及全屏问题
16lz
2021-01-23
一、图像全屏问题
首先找到CameraBridgeViewBase文件的 protected void deliverAndDrawFrame(CvCameraViewFrame frame)方法,阅读源码发现该方法主要实现的就是相机预览图的绘制,核心代码如下:
if (bmpValid && mCacheBitmap != null) { Canvas canvas = getHolder().lockCanvas(); if (canvas != null) { canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR); if (mScale != 0) { canvas.drawBitmap(mCacheBitmap, new Rect(0, 0, mCacheBitmap.getWidth(), mCacheBitmap.getHeight()), new Rect((int) ((canvas.getWidth() - mScale * mCacheBitmap.getWidth()) / 2), (int) ((canvas.getHeight() - mScale * mCacheBitmap.getHeight()) / 2), (int) ((canvas.getWidth() - mScale * mCacheBitmap.getWidth()) / 2 + mScale * mCacheBitmap.getWidth()), (int) ((canvas.getHeight() - mScale * mCacheBitmap.getHeight()) / 2 + mScale * mCacheBitmap.getHeight())), null); } else { canvas.drawBitmap(mCacheBitmap, new Rect(0, 0, mCacheBitmap.getWidth(), mCacheBitmap.getHeight()), new Rect((canvas.getWidth() - mCacheBitmap.getWidth()) / 2, (canvas.getHeight() - mCacheBitmap.getHeight()) / 2, (canvas.getWidth() - mCacheBitmap.getWidth()) / 2 + mCacheBitmap.getWidth(), (canvas.getHeight() - mCacheBitmap.getHeight()) / 2 + mCacheBitmap.getHeight()), null); } if (mFpsMeter != null) { mFpsMeter.measure(); mFpsMeter.draw(canvas, 20, 30); } getHolder().unlockCanvasAndPost(canvas); }}
因此将绘制代码重新设计后可以解决图像旋转及全屏问题,解决如下:
if (bmpValid && mCacheBitmap != null) { Canvas canvas = getHolder().lockCanvas(); if (canvas != null) { canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);// 修改预览旋转90度问题canvas.rotate(90, 0, 0);float scale = canvas.getWidth() / (float) mCacheBitmap.getHeight();float scale2 = canvas.getHeight() / (float) mCacheBitmap.getWidth();if (scale2 > scale) { scale = scale2;}if (scale != 0) { canvas.scale(scale, scale, 0, 0);}canvas.drawBitmap(mCacheBitmap, 0, -mCacheBitmap.getHeight(), null);// 修改预览旋转90度问题end if (mFpsMeter != null) { mFpsMeter.measure(); mFpsMeter.draw(canvas, 20, 30); } getHolder().unlockCanvasAndPost(canvas); }}
亲测这个方案可行,但是仅仅适用于竖屏并且是后置摄像头,如果改为前置摄像头、横屏模式则不行,还需要进一步修改,考虑到能不修改源码尽量不修改的原则,继续深挖代码。我们尝试在mScale上做文章,JavaCameraView类中有这么一段代码:
if ((getLayoutParams().width == LayoutParams.MATCH_PARENT) && (getLayoutParams().height == LayoutParams.MATCH_PARENT)) mScale = Math.min(((float)height)/mFrameHeight, ((float)width)/mFrameWidth);else mScale = 0;
这里决定了相机获取图像映射到画布上的缩放比例,很明显取最小值是要保证图像缩放,全部显示在画布上。
修改为裁剪图像,只显示其中间部分,如下:
if ((getLayoutParams().width == LayoutParams.MATCH_PARENT) && (getLayoutParams().height == LayoutParams.MATCH_PARENT)) { if (isShowFullPreview()) { mScale = Math.min(((float) height) / mFrameHeight, ((float) width) / mFrameWidth); } else { mScale = Math.max(((float) height) / mFrameHeight, ((float) width) / mFrameWidth); }} else { mScale = 0;}
还有其他解决方案,有兴趣的童鞋可以继续深挖。比如mFpsMeter对象的处理
二、图像旋转问题
旋转问题分为横屏、竖屏分开处理,
1、AndroidManifest.xml文件中指定Activity的屏幕方向:android:screenOrientation。
2、Activity继承CvCameraViewListener2接口,实现public Mat onCameraFrame(CvCameraViewFrame inputFrame)方法。如下:
@Override public Mat onCameraFrame(CvCameraViewFrame inputFrame) { Mat frame = inputFrame.rgba(); if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT) { if (mOpenCvCameraView.isFrontCamare()) { Core.rotate(frame, frame, Core.ROTATE_90_COUNTERCLOCKWISE); Core.flip(frame, frame, 1); } else { Core.rotate(frame, frame, Core.ROTATE_90_CLOCKWISE); } } else { if (mOpenCvCameraView.isFrontCamare()) { Core.flip(frame, frame, 1); } } return frame; }
更多相关文章
- Android 源代码在线查看(转)
- Android中获取网页表单中的数据实现思路及代码
- android安装包apk文件反编译代码
- GDB在线调试Android Framework Native C/C++代码
- android 发送短信,彩信,邮件代码
- 关机重启代码
- Android 重启应用代码
- 蓝牙原理Android代码实现
- Android ValueAnimator和ObjectAnimator的高级用法(代码实现)